Abstract: Objective To explore the effects and related mechanisms of Interleukin-2 (IL-2) on macrophage polarization. Methods Comparing with the recombinant mouse IL-4 (rmIL-4), rmIL-2 was used to treat the mouse macrophage cells RAW 264.7. Then, the cell markers of M1 and M2 expression were detected by Real-time PCR and Western blot. And the percentage of M1 or M2 macrophages was analyzed by flow cytometry. Additionally, the activation of Jak3 and Stat5 was also analyzed by Western blot. Results The expression of M1 maekers (IL-1β, IL-12, TNF-α and iNOS) was significantly up-regulated in RAW 264.7 cells after treated with IL-2. And the IL-2 treatment increased the percentage of M1 macrophages from 3.2% to 24.6%. Further, IL-2 significantly enhanced the phosphorylation of Jak3 and Stat5. Conclusions IL-2 could promote M1 polarization of macrophages, probably via the Jak3-Stat5 signaling pathway.

Key words: IL-2, IL-4, macrophage, polarization, Jak3-Stat5 signaling